Utilization of hardwood in biorefinery: A kinetic interpretation of pilot-scale hot-water pretreatment of Paulownia elongata woodchips

Hot water extraction of summer-harvested Paulownia elongata in a pilot-scale reactor of 1.84 m³ was investigated at 160°C for 2.5 h. Monomeric sugars, carboxylic acids, and xylo-oligomers were the major components in the hot water extract. Unlike the extraction results of fall/winter harvested Paulownia elongata, glucose was the dominant monosaccharide in the extraction liquor especially during early stage of the extraction of the wood harvested during active growth in summer. The maximum concentration of glucose recorded was 0.013 mol/L. The xylo-oligomers concentration, reaching up to 0.012 mol/L, were the main oligosaccharides. Concentrations of furfural and hydroxymethylfurfural (HMF) increased with extraction time and reached a maximum value of 0.0053 mol/L and 0.004 mol/L, respectively, by the end of extraction. Pseudo-zeroth order rate kinetic models were employed to describe the change in dissolved solids, xylooligomer, monomer sugars, acids, furfural, and HMF in the hot water extract.